How CGI Scripting Works

On most servers, CGI scripts live in a directory named cgi-bin. The script is executed when the script's URL is requested by a browser.

Anything that the script sends to STDOUT will be sent to the browser. The string "Content-type: text/html\n\n" should be the first thing sent. After that, anything goes; but typically, valid HTML tags for a valid HTML document are sent.

Input is sent to the script by creating an HTML form whose ACTION specifies the script's URL.

When a script receives the data from the form, it has to parse out the different strings and convert all of the modified characters. We saw a simple C program that can perform these tasks. The CGI library for PERL (see the next page) makes the conversion easy for PERL scripts.

If you were doing this on a real Web site, you would typically store the results from each survey into a text file or a database so that you could look at the results later. That's easy to do from either a C program or a PERL script.